Production of coke and gas in chamber ovens



Dec. 19, 1933. c sTlLL 1,940,567

PRODUCTION OF COKE AND GAS IN CHAMBER OVENS Filed Feb. 5, 1931 a/wey Patented Dec. 19, 1933 v r PRODUCTION F COKE AND GAS I I CHAMBER ovens" I Carl Still, Recklinghausen; Germany Application Februaryb, 1931,,Serial No. 513,741, and in Germany February 11, 1 930 6 Claims. (c1. 202-10) The invention consists in improvements in the production of coke and gas from solid fuel in closedintermittently operated chambers, which I are heated through the side walls. The'subject 'of the invention is a process by which the gases and volatile products of distillation can be drawn off by suction from a collecting space provided above 'the charge and also from the interior of the body of the fuel. By the practice of the process according to the invention, the

quality and yield of the coke and also of the volatile products, such as coal gas, tarrand hydrocarbons, are improved The process will be explainedapplied to a horizontal coke oven. r v

In theaccompanying drawing, which repre sents an apparatus for carrying out theprocess according to the invention:

Fig. 1 is a vertical section through the centre of a coke oven chamber, of which ma a portionincluding the front endis shown Fig. 2 is a, verticallcrosaseetion comprising two adjacent oven chambers and two heating walls. I I f In Fig. 2 the chamber on the left is in a condition corresponding to the first stage and the chamber on the right in a condition corresponding in the second stage of the process.

The chamber, 1 which is heated in the usual manner on both sides by walls 2, and is closed at its front by a door 3, has the usual openings 5 (only one otwhich is shown) in the roof 4 for introducing the chargeof coal and'an'opening Bior leading away the gas and is connected by the ascension pipe '7 with a gas and tar main 8. Where the ascension pipe? opens into the main ;8, aivalve 9 is providedin the usual manher and is formed to provide a liquid seal, The framing of themain salso. carries a gas collecting tube lilexten'ding overthe whole length or" the battery. iThe oven chamber 1 contains the charge of coal to be coked which, in the usual manner, is filled up to a level such that above the surface 11 there is a free gas, collect ing space 12 in connection with the gas discharge opening 6. r Q

In the oven roof 4 there are disposed between theopenings 5 and 6 a number, about 8 to 12 or more, of iron boxes 1&1 inserted over the whole length of the chamber at uniform distances apart, which boxes are closed gas-tight by covers 13 provided with water seals.- Fresh sealing,

water is introduced constantly through connections 15 from pipes 16 disposed on the roofand flowsinto the boxes 14." Each of the boxes 14' the pipe 13 under the, by-pass 19 serves to discharge any liquids and condensed vapors enteris connected by aside connection 17 with a gas collecting pipe ,18 placed in thereof 4 parallel to the longitudinal axis of the chamber, and outside the oven is connected by a, by-pass pipe 6 19 with the gas collecting pipe llll' The' lower. 1 part of the by-pass pipe 19 is formed to provide a water seal which'when a bell 2 01s lowered, shutsjofi the connection between the pipe 18 and the collectingpipe 10. The sealing water is introduced through'a'pip'e 21.

A throttling member 22 in theby-pass pipe 19 by suitable adjustment enables the gaseous pressure in. every separate pipe 18 to be regulated: a valvecontrolled pipe 23 at the end of ingthepipelS.

In the bottom of each box i l-there is a tubular member 2 projecting upwardly within the box and a downwardly projecting tube 25 of the same diameter, which together guide and hold a concentric pipe: 26, disposed in them. After. the cov'erl13 has been removed, the tube 26 can, as required, be'inserted or removed. The upper end "of the tube 26 projecting intothe box'l l carries a bell 27, which, with the casing of the box 14 and its inner tube24, forms a water seal, by which the interior of the tube 26issealed from its external surface. The sealing'water is also takenthrough the connections 15 from the :pipe 16, asan overflow of the sealingdevice' of the cover 13, and flows through the sideconnections 17 into the pipe 18 and, finally, through the discharge pipe 23.

.The lower end of the tube 26passes through the gas-collecting space 12 or" the oven chamber and extends still further for a distance'of about 300 to 500 mm. below thesurface 11 ofthe charge of coal, and is'there connected to a tu-' .bular. duct 28 formed ,in the body of thefc oal, I

which duct extends approximately through the whole depth of the coal in the central portion between the two heated chamber walls. The duct 28 and the tube ZGiorm a passage for. the

purpose of drawing off the volatile products of distillation by suction from the interior of the vices, so that the gaseous pressure in each can be maintained at a definite value independently of that in the other.

The working or" the previously described apparatus in order to carry out the process according to the invention is as follows:

The oven, chambers are constantly heated by the heating walls 2, preferably in the same manher and to the same extent as is usual in the production of coke. The tubes 26 are removed from the oven chamber, as further explained later, before the charge has been finally coked and before the coke has been discharged. After the discharge of'the coke, while both doors 3 are closed and the, main 8 has been cut oh by the apparatus 9, and the pipe 10 by the water sealed bell 20 from the oven chamber, the coal to be coked is charged into the oven chamher in the usual manner and the suriace 11 of the coal levelled. The so-called charging gases produced during the coal charging are preferably led away through the ascension pipe 7 by ineans of any suitable apparatus (not shown).

Then, in order to produce the ducts 28, an iron ro'd having a pointed end is pushed through the guiding tubes 24, 25 in box 14 vertically into the charge of coal and then afterwards withdrawn. The vertical position of the ducts 28 produced and the symmetrical pressure exerted around them by the charge of coal, ensure that the ducts formed remain intact. The take-off pipes 26 are inserted from above into the boxes 14 so that their lower ends are-pressed into the ducts 23 and make a sufficiently tight connection with the latter and after this the covers 13 are replaced;

v The discharge-of the gases driven off during charging, which up to this time have been withdrawn through the ascension pipe 7, is now stopped. The gasis first prevented from entering the main 8, which is shut off by the valve 9 from the oven chamber. The by-pass pipe 19 is then opened by raising the bell 20 and the gas collecting pipe 118 and all the boxes 14 connected thereto are brought into connection with, the pipe 10, wherein a relatively slight sub-atmospheric pressure is maintained. In this way, the volatile products of distillation are drawn off by suction through the ducts 28.

An important characteristic of the invention consists in the feature that, during the suction operation, in the ducts 28 and the tubes 26 or, respectively, in the boxes 14 in connection with the latter, a partial vacuum or suction is maintained the degree of which is varied strictly in dependence, as described later, on the progress of the coking'within the charge of coal. The necessary regulation for this is effected by suitable and variable adjustment of the throttling member, such as a damper or valve 22 in the by-pass 19.

, As an" example 'of the application of the method the treatment of an ordinary coking coal is assumed which during the coking produces well-defined coking seams, that is plastic zones of bituminous composition which form the boundary between the outer part of the charge which has been converted to finished glowing coke and the inner unaltered part. This kind of coal includes according .to experience, coals of medium, moderate and small content in volatile constituents; for example, most'of the Westphalian coals belong to this class.

In the treatment of thiscoal, the first stage of the process is introduced directly after the beginning of the, operation, by the suction being adjusted so that the gas pressure in the space 12, when measured by the usual water gauge which is under the influence of the atmosphere on its other end amounts to 0 min. water gauge, that is to say it is equal to the atmospheric pressure. For this purpose usually a moderate partial vacuum of about 10 to 30 mm. of a water gauge is suificient in the boxes 14.

After a relatively short time, about one hour, a coking seam 29 is formed in the body of the coal very closely adjacent to the heated walls of the chamber, so that the condition is similar to thatrepresented in the left-hand chamber of Fig. 2. Also,-the surface 11 of the coal has been converted, mainly by heat radiated from the arch of the chamber, to a kind of coking seam. Within this coking seam there is a quantity, at first still unaltered and relatively cool, of coal 30, of which the temperature is not substantially higher than 100 C., until the whole of the water content has been driven 01f, which by experience lasts at least during half of the carbonizing period. Outside the coking seam 29 there is finished, highly glowing, coke 31. As soon as this condition has been set up, and this is an important step and further characteristic of the invention, the partial vacuum, maintained in the ducts 28 of the coal, and which is effective in drawing off the gas, is considerably increased; this reduction of pressure is made possible by the water seal in the boxes 14 and by the apparatus 9. The gaseous pressure in the outer space 12 is maintained, as previously, at 0 mm. of a water gauge. Use is then made of the fact that the whole coking seam forms a nearly tight closure between the inner and outer parts of the body of the coal and allows considerably increased differences of gas pressure to be maintained between these two parts. The value'to which the partial vacuum is to be increased depends essentially on the actual conditions and requirements of the individual cases, which are determined by: The thickness of the coal layers in the horizontal direction from which the charge is to be drawn off; and which, in the first place, depends on the diameter of the chamber, in the second place on the distance between the ducts 28; the packing and granulation of the coal; also, more especially on the rate at which the products of distillation to ,be drawn oiT are generated, which again depends on the kind of coal and also on the heating properties of the chamber.

For example, assuming a totalcarbonizing period of 24 hours,,the partial vacuum is increased in the boxes 14 from the above-named very small initial value to,at the end of the first hour, about 50 mm. of a water gauge, and.

is progressively increased-until at the end of the tenth or twelfth hour, that is approximately at the middle of the carbonizing period, it is approximately from 100 mm. to 150 mm. At the same time, care must be taken that the gaseous pressure in the gas collecting space, 12

of coke 31 outside the coking seam includes,

towards the end of this period of operation, the greater part of the charge; the quantity of the charge of coal 30 which remains unaltered within, the coking seam 29 has been reduced to Ill) a smalliproportion' of its originalqua'ntity; The

whole coking seam 29 forms a sort of envelope surrounding the ducts 28; seams 29 are forced from bothsidestowards the ducts 28 until they are quite close to the latter, possibly still closer than is shown in the chamber on the right of Fig. 2. The first stage of the process is completed under these conditions.

Thesecond-stage of the process is introduced by the above-described considerable partial vacuum, for example 150 mm. watergauge or more, prevailing at the end of the first stage, being remove'd'enti-rely'from theboxes 14 or the passages-and ducts 26, 28, and'the pressure maintained in these parts being made equal to the pressure in the external spaces 12 which is maintained practically "equal to that of the external atmosphere-i. e., at 0' mm. of a water gauge as before mentioried: This operating condition is maintained until'the coking is fcom gauge. It is to be considered,however,- that the suction effect, which is consequently considerably weakened in the ducts 28 of the coal, may not be suiiicient sir'nultaneously' to remove, as previously, also the gases from the outer space 31'. It is,"therefore, necessary, in order thatthe gaseous pressure in the gas collecting space 12 shouldremain at atmospheric or 0 mm. and that no accumulation of gas should here arise,to draw off gases at the same time through the ascension pipe 7 into the main 8. In order to carry out the process more advantageously than in theabove described method, at'the beginning or the second stage the'tubes 26 are removed, so that the ducts 23 are brought into direct connection with the space 12 at the upper surface 11 of the coal, and then all the volatile products of distillation are drawn off uniformly from this common space 12 through the ascension pipe '7 into the -1nainj8. For this purpose the gas stream from the pipes 26 and 18 to the main 10 is shut off from thepipe 10by loweringthe bell 20 into the by-pass 19 and the closing device or.

valve 9 between the ascension pipe 7 and the main 8 is opened. i

The described changes which form itheessential point of the invention, in the partial vacuum, applied to the interior of the coal for drawing off the gases, arejustified by the changes taking place in the charge of coaljitself and the alterationscaused from time to time, thereby in the properties of the distillation products drawn ofif. Atthe beginning of the first stage, that is, after the'coking seam 29 (shownjon the left of Fig. 2)

- has been'formed, the character of thecoal 30 within it is essentially unaltered from its original condition on charging, and the "paths for the products of distillation flowing from the body of the coal are to a very large extent freed.

A moderatesuction or sub-atmospheric pressure is, consequently, now sufficient for drawing off thegases from the interior. In the further course of the first stage, tar vapors are continually being condensed by flowing through the cool body of coal and, consequently, the passages for the flow of the products are constantly becoming more choked. Therefore, it is necessary Finally, the coking ,drawingoif the gases from the ducts.

that thesuction shouldbe increased, that isithe pressureloweredstill further below the atmosphere; This is due to the fact that, towards the end of the first stage, the tar vapors find, thegreatest-resistance to their flow owing to this flow occurring mainly in: a narrow-zone parallel to the middle plane between two adjacent ducts 28. At this period, however, the largest portion of the bituminous constituents present has been evaporated and drawn off; The further yield of these products is small: 1 h i Theinvention utilizes this fact by stopping the suction from this time onwards from the interior of the charge. The distillation products which from'thistime are-'stilleifectively formed and which are developed from the space enclosed by the coking seams 29 are forced by their own pressure into theducts 28 andfrom them led into the'spacelZ and remainfthereforeessentially in the same condition in Whichthey were formed.--

At 'theend' ofthe carbonizing period, when the whole body of coal has been coked, the'main 8 islcut off'from the ascension tube 7 byclosing the device 9- and thereby the suction-is fina'lly stopped. The doors 3 are opened and reproducts of distillation developed outside the 0 coking seam 29can, if required, bedrawnoff through the ascension pipe 7 and the mainB. In this case,'obviously, a gaseous pr'essure equal to atmospheric must be'm'aintained constantly. in the gas collecting-space 12'. i 11 By this means, two kinds of gases are obtained s at the same time, which, since during this pro'c-v V ess very different suctions are applied for draw ing off-the gases from the inner and outerspace's, aresharply separated. The gas drawn off from the inner space is a valuabledistillation gas with considerable content fof benzol vapor of. which the heating value atthe commencement oi the first stage is about "7500 calories per cubic metre; at the end of this, stage, about5500 cal oriespercubic metre. The gas produced at the beginning of the second stagefwhichapproxie mates closely to the endof thefirststage, has a similar high heating value of 5500 calories per cubic m'et're andth is value is reducedat the end of thesecondst'age to about 3000 calories per cubic'metre f i 1 "Theprocess described lcanfalso be employed chamber, thetubes 26are inserted from theoven roof in the manner previously described,-so that their lower ends .extend into the ducts'so formed.

The operation is carried-out in other respects int the same manner as in the above example; only on accountof the usual greater density of the coal cake a highervacuum must be employed in V 1 The following advantages are obtained by the process according to-the invention:-

(1) In the production of a valuable metallurgical coke essentially improved by-products are obtained, more particularly a valuable tar with rich content in benzene and thin clear oils withlittle pitch and scarcely anynaphthalene.

v(2) The transference of .heat'from the heat-. ingwalls to the charge of. coal is very much improved on account of the strong flow of gases through the charge due to the. high partial vacuum, so that the carbonizingperiod is considerably reduced, by a quarter to .a third.

(3) Since a considerable proportion of. all the distillation gases and volatile matters produced at low temperature are led away from the ducts externally, less heat, is required for heating the oven and also less work required in the gas condensing plant and smaller plants can be used ,for this purpose. Y

(4) The high partial vacuum is maintained in the ducts 28 for that portion of the carbonizing period during which only cool gases and vapors traverse the tubes 26, and this fact together'with the possibility that these tubes can be removed before the end of the carbonizing period ensures that the said tubes and the take-off pipes connected with them are not injured by the operation and simplifies the carrying out of the process.

What I claim is: '1. The process for the production of coke and gas in intermittently operated externally heated oven chambers containingacharge of coal and, provided with a gas collecting space above the surface of the charge and with interior ducts, which comprises drawing volatile distillation products separately from the interior of the body of the coal and from the gas collecting space, constantly maintaining the gas pressure in the collecting space approximately equal to that of the atmosphere and gradually i reducing the pressure in the ducts of the charge from the start of the coking process to at least 100 mm. of a water gauge below atmospheric pressure.

, I 2. The process for the production of coke and gradually reducing the pressure in the body of.

the charge from the start of the coking process toat least 100 mm. of a water gaugebelowatmospheric pressure, and finally near the end of the coking process raising said pressure to substantially zero mm.

3. The process for the production of coke and gas in intermittently operatedexternally heated oven chambers containinga charge of coal and provided with a gas collecting space abovethe surface of the charge and with interior ducts; which consists in forming vertical ducts in the interior of the body of the coal, withdrawing" separately the. volatile distillation products from thegas collecting space and fromthe' ducts in the interior of the charge, maintaining pressure in the gas collecting space. approximately equal to that of theatmosphere and adjusting pressure in the ducts whereby atthe start of the coking, it is moderately sub-atmospheric, reducing said pressure to at least mm. of a water gauge below atmospheric during the further course of the coking process, and raising said pressure in said ducts to substantially atmospheric before the end of the coking process.

, 4. The process for. the production of coke and gas in intermittently operated externally heated oven chambers containing a charge of coal and provided with a gas collecting space above the surface of the charge and with interior ducts, whichc'onsists in forming vertical ductsin the interior of the, body. of the coal, withdrawing separately the volatile distillation products from the gas collecting space and from the ducts in the interior of the charge, maintaining pressure in the gas collecting spaceapproximately equal to that of the atmosphere and adjusting pressure in the ducts whereby at the start of the coking it is moderately sub-atmospheric and in the further course of the coking process is re-, duced to at least-100 mm. of a water gauge below atmospheric. a

5. The process of producing coke and gas in intermittently operated externally heated oven chambers containing a charge of coaland provided with a gas collecting space above-the surface of the charge and with interior ducts, which consists in withdrawing separately the volatile distillation products from the gas colgauge. r

6. The process of withdrawing distillation products of different volatility from a charge of coal in a horizontal, externally heated chamber oven, which comprises charging coal loosely into said chamber, leaving a gas collecting space between the surface of the charge and the oven roof, forming vertical ducts in the charge, withdrawing volatile distillation products separately from the interior of the body of the charge through said ducts and from the gas collecting space above the charge, constantly maintaining lecting space and from the interior of the charge 7 the pressure in the gas collecting space substantially equal to that of the atmosphere throughout the coking period, and applying progressively increasing suction below atmospheric pressure .to said ducts as the coking process progresses throughout the coking period.

CARL STILL.

Patent No. 1,940,567. December 19, 1933.

CARL STILL.

it is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 4, line 123, claim 5, after "interior" insert ducts; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 15th day of May, A. I). 1934.

Bryan M. Battey (Seal) Acting Commissioner of Eetents. 

